• Lhermitte's phenomenon is a transient, sensory symptom which likens an electric shock that radiates down the spine or into the limbs.

• The sensation is triggered by neck flexion.  The frequency with which they occur varies and the slightest movement of the head or neck may trigger it.

• This phenomenon occurs most frequently with multiple sclerosis, but can also be seen with other lesions of the cervical cord, including tumors, disc herniation, post-radiation myelopathy, and following trauma.

References

• Kanchandani R, Howe JG.  "Lhermitte's sign in multiple sclerosis: a clinical survey and review of the literature." Journal of Neurol Neurosurg Psychiatry. 1982;45(4):308-12.